Azure SQL PaaS Failover Scenario and Cost

Hi,

I have a few questions regarding Azure SQL PaaS failover, pricing, and integration with private endpoint:

If I configure a Failover Group that contains 10 SQL databases, will the entire failover group automatically failover if only one of the databases in the group becomes unavailable? Or does automatic failover only happen if the entire SQL server (or all databases) are unavailable?
I understand that Failover Group supports auto-failover, but it seems that this only applies when the failover is Microsoft-managed, which might take up to an hour or more depending on the outage. If I’m using a custom-managed failover, is there a way to enable automatic failover behavior in that context? Would I need to set up any custom metrics, alerts, or automation (e.g., with Azure Monitor and Logic Apps) to support this kind of proactive failover?
If my SQL databases are all in an elastic pool. After I provision a secondary elastic pool in the secondary region, and enable geo-replication for each database, will the cost of the geo-secondary databases be based solely on the secondary elastic pool’s pricing tier, with no additional per-database cost?
Is there any extra charge specific to the Failover Group itself (other than the cost of the geo-secondary databases)?
If I have SQL servers configured with private endpoints, and I’ve already created a secondary SQL server in another region and linked both SQL servers to the same private DNS zone, are there any additional steps required to prepare for failover? After failover, do I need to manually update any connection strings or DNS records, since I know failover group will automatically update connection string, but how about SQL server itself with private endpoint?
Are there any best practices for failover testing in such a setup (e.g., temporarily failing over and validating connectivity via private endpoint)

Thank you!